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Diffstat (limited to 'llvm/docs/LangRef.rst')
-rw-r--r-- | llvm/docs/LangRef.rst | 65 |
1 files changed, 31 insertions, 34 deletions
diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst index e063f6bd35f..800c51aae57 100644 --- a/llvm/docs/LangRef.rst +++ b/llvm/docs/LangRef.rst @@ -5352,40 +5352,6 @@ Some important flag interactions: - A module with ``Objective-C Garbage Collection`` set to 0 cannot be merged with a module with ``Objective-C GC Only`` set to 6. -Automatic Linker Flags Module Flags Metadata --------------------------------------------- - -Some targets support embedding flags to the linker inside individual object -files. Typically this is used in conjunction with language extensions which -allow source files to explicitly declare the libraries they depend on, and have -these automatically be transmitted to the linker via object files. - -These flags are encoded in the IR using metadata in the module flags section, -using the ``Linker Options`` key. The merge behavior for this flag is required -to be ``AppendUnique``, and the value for the key is expected to be a metadata -node which should be a list of other metadata nodes, each of which should be a -list of metadata strings defining linker options. - -For example, the following metadata section specifies two separate sets of -linker options, presumably to link against ``libz`` and the ``Cocoa`` -framework:: - - !0 = !{ i32 6, !"Linker Options", - !{ - !{ !"-lz" }, - !{ !"-framework", !"Cocoa" } } } - !llvm.module.flags = !{ !0 } - -The metadata encoding as lists of lists of options, as opposed to a collapsed -list of options, is chosen so that the IR encoding can use multiple option -strings to specify e.g., a single library, while still having that specifier be -preserved as an atomic element that can be recognized by a target specific -assembly writer or object file emitter. - -Each individual option is required to be either a valid option for the target's -linker, or an option that is reserved by the target specific assembly writer or -object file emitter. No other aspect of these options is defined by the IR. - C type width Module Flags Metadata ---------------------------------- @@ -5422,6 +5388,37 @@ enum is the smallest type which can represent all of its values:: !0 = !{i32 1, !"short_wchar", i32 1} !1 = !{i32 1, !"short_enum", i32 0} +Automatic Linker Flags Named Metadata +===================================== + +Some targets support embedding flags to the linker inside individual object +files. Typically this is used in conjunction with language extensions which +allow source files to explicitly declare the libraries they depend on, and have +these automatically be transmitted to the linker via object files. + +These flags are encoded in the IR using named metadata with the name +``!llvm.linker.options``. Each operand is expected to be a metadata node +which should be a list of other metadata nodes, each of which should be a +list of metadata strings defining linker options. + +For example, the following metadata section specifies two separate sets of +linker options, presumably to link against ``libz`` and the ``Cocoa`` +framework:: + + !0 = !{ !"-lz" }, + !1 = !{ !"-framework", !"Cocoa" } } } + !llvm.linker.options = !{ !0, !1 } + +The metadata encoding as lists of lists of options, as opposed to a collapsed +list of options, is chosen so that the IR encoding can use multiple option +strings to specify e.g., a single library, while still having that specifier be +preserved as an atomic element that can be recognized by a target specific +assembly writer or object file emitter. + +Each individual option is required to be either a valid option for the target's +linker, or an option that is reserved by the target specific assembly writer or +object file emitter. No other aspect of these options is defined by the IR. + .. _intrinsicglobalvariables: Intrinsic Global Variables |